1. Private messages on this site

Check this if you want other users be able to send you private messages on the site.

Note: the Sender will also need to have this checked, otherwise he would never be able to receive a response.

2. Emails through a message form that will NOT reveal my email address. [Admin]

If this is checked, other users will be able to send you emails. They will do so through a contact from that will not reveal your email address. Your email address will not be revealed unless you reply to them (by sending them an email from your address.)